import type { StructuredToolInterface } from "@langchain/core/tools";
import type { BaseConnector } from "../../connectors/base.js";
import type { IServerManager } from "../types.js";
import type { SchemaOutputT } from "./base.js";
import { z } from "zod";
import { logger } from "../../logging.js";
import { MCPServerTool } from "./base.js";

const ConnectMCPServerSchema = z.object({
  serverName: z.string().describe("The name of the MCP server."),
});

export class ConnectMCPServerTool extends MCPServerTool<
  typeof ConnectMCPServerSchema
> {
  override name = "connect_to_mcp_server";
  override description =
    "Connect to a specific MCP (Model Context Protocol) server to use its tools. Use this tool to connect to a specific server and use its tools.";
  override schema = ConnectMCPServerSchema;

  constructor(manager: IServerManager) {
    super(manager);
  }

  async _call({ serverName }: SchemaOutputT<typeof ConnectMCPServerSchema>) {
    const serverNames = this.manager.client.getServerNames();

    if (!serverNames.includes(serverName)) {
      const available =
        serverNames.length > 0 ? serverNames.join(", ") : "none";
      return `Server '${serverName}' not found. Available servers: ${available}`;
    }

    if (this.manager.activeServer === serverName) {
      return `Already connected to MCP server '${serverName}'`;
    }

    try {
      let session = this.manager.client.getSession(serverName);
      logger.debug(`Using existing session for server '${serverName}'`);
      if (!session) {
        logger.debug(`Creating new session for server '${serverName}'`);
        session = await this.manager.client.createSession(serverName);
      }
      this.manager.activeServer = serverName;
      if (this.manager.serverTools[serverName]) {
        const connector: BaseConnector = session.connector;
        const tools: StructuredToolInterface[] =
          await this.manager.adapter.createToolsFromConnectors([connector]);
        this.manager.serverTools[serverName] = tools;
        this.manager.initializedServers[serverName] = true;
      }
      const serverTools: StructuredToolInterface[] =
        this.manager.serverTools[serverName] || [];
      const numTools: number = serverTools.length;
      return `Connected to MCP server '${serverName}'. ${numTools} tools are now available.`;
    } catch (error) {
      logger.error(
        `Error connecting to server '${serverName}': ${String(error)}`
      );
      return `Failed to connect to server '${serverName}': ${String(error)}`;
    }
  }
}
